Integrated active-matrix light emitting pixel arrays based devices by laser-assisted bonding

Abstract

Integrated active-matrix light emitting pixel arrays based displays and methods of fabricating the integrated displays are provided. One of the methods include: forming first color light emitting diodes (LEDs) and respective intermediate metallic layers on a first substrate, integrating the first color LEDs with pixel circuits in a backplane device, injecting laser pulses into particular first color LEDs, such that each particular first color LED is individually separated from the first substrate and locally bonded with a respective pixel circuit through a respective intermediate metallic layer, and removing the first substrate from the backplane device. The backplane device bonded with the particular first color LEDs can be further bonded with other different color LEDs formed on other substrates. Other first color LEDs without exposure of the laser pulses are removed with the first substrate and can be further used to integrate with another backplane device bonded with another color LEDs.

What is claimed is: 
     
       1. A method of fabricating an integrated device, comprising:
 forming an array of first light emitting elements and respective first intermediate metallic layers on a first substrate, wherein each of the first light emitting elements comprises first semiconductor layers epitaxially grown on the first substrate and is configured to emit light with a first color, the first semiconductor layers comprising a first conductive outer layer on a side of the first semiconductor layers further from the first substrate, a respective first intermediate metallic layer being formed on the first conductive outer layer; 
 integrating the array of first light emitting elements formed on the first substrate with an array of pixel circuits in a backplane device by contacting the respective first intermediate metallic layers on the first light emitting elements to conductive outer layers of the pixel circuits, the pixel circuits being conductively isolated from each other; 
 injecting laser pulses into particular first light emitting elements from the array of first light emitting elements, such that each of the particular first light emitting elements is individually separated from the first substrate and locally bonded with a respective particular first pixel circuit of the array of pixel circuits through a respective particular first intermediate metallic layer; and 
 removing the first substrate from the backplane device, with the particular first light emitting elements remaining bonded with and conductively coupled to the respective particular first pixel circuits in the backplane device through the respective particular first intermediate metallic layers. 
 
     
     
       2. The method of  claim 1 , wherein the first semiconductor layers comprise a first buffer layer directly formed on the first substrate, and
 wherein injecting laser pulses into particular first light emitting elements comprises controlling the laser pulses such that
 the first buffer layer is decomposed and separated from the first substrate and 
 heat generated in the particular first light emitting elements by the laser pulses is locally transferred to the respective particular first intermediate metallic layer to cause eutectic bonding between the first conductive outer layer of the particular first light emitting element and the conductive outer layer of the respective pixel circuit through the respective particular first intermediate metallic layer. 
 
 
     
     
       3. The method of  claim 1 , wherein adjacent particular first light emitting elements are separated from each other by one or more additional first light emitting element in the array of first light emitting elements, and
 wherein removing the first substrate from the backplane device comprises:
 removing the first substrate together with the additional first light emitting elements remaining formed on the first substrate. 
 
 
     
     
       4. The method of  claim 3 , further comprising:
 integrating the additional first light emitting elements remaining formed on the first substrate with an array of second pixel circuits bonded with an array of second light emitting elements, the array of second light emitting elements being bonded on respective particular second pixel circuits of the array of second pixel circuits and separated from one another by at least one additional second pixel circuit, wherein respective first intermediate metallic layers on the additional first light emitting elements are attached to conductive outer layers of the additional second pixel circuits, and wherein each of the second light emitting elements is configured to emit light with a second color different from the first color; 
 injecting the laser pulses into second particular first light emitting elements in the additional first light emitting elements, such that each of the second particular first light emitting elements is individually separated from the first substrate and locally bonded with a respective second pixel circuit of the additional second pixel circuits through a respective second particular first intermediate metallic layer; and 
 removing the first substrate from the array of second pixel circuits, with the second particular first light emitting elements remaining bonded with and conductively coupled to the respective second pixel circuits of the additional second pixel circuits through the respective second particular first intermediate metallic layers, 
 wherein the array of second pixel circuits is
 in a second backplane device different from the backplane device, or 
 in a second region of the backplane device that is different from a first region including the array of pixel circuits. 
 
 
     
     
       5. The method of  claim 4 , wherein the adjacent particular first light emitting elements are separated from each other by one of the second particular first light emitting elements and a third particular first light emitting element in the array of first light emitting elements,
 wherein removing the first substrate from the array of second pixel circuits comprises: removing the first substrate together with the third particular first light emitting elements that remain formed on the first substrate, 
 wherein the method further comprises:
 integrating the third particular first light emitting elements remaining formed on the first substrate with an array of third pixel circuits, wherein a second array of second light emitting elements and an array of third light emitting elements are bonded on respective particular third pixel circuits of the array of third pixel circuits, wherein each of the third light emitting elements is configured to emit light with a third color different from the first color and the second color, wherein adjacent third light emitting elements bonded on the array of third pixel circuits are separated from each other by one of the second array of second light emitting elements and an additional third pixel circuit, and wherein respective third particular first intermediate conductive layers on the third particular first light emitting elements are attached to conductive outer layers of the additional third pixel circuits; 
 injecting the laser pulses into the third particular first light emitting elements, such that each of the third particular first light emitting elements is individually separated from the first substrate and locally bonded with a respective additional third pixel circuit of the additional third pixel circuits through a respective third particular first intermediate metallic layer; and 
 removing the first substrate from the array of third pixel circuits, with the third particular first light emitting elements remaining bonded with and conductively coupled to the respective additional third pixel circuits through the respective third particular first intermediate metallic layers, 
 wherein, on the array of third pixel circuits, each of the third particular first light emitting elements is adjacent to a respective second light emitting element of the second array of second light emitting elements and a respective third light emitting element of the array of third light emitting elements, and 
 wherein the array of third pixel circuits is
 in a third backplane device different from the backplane device and the second backplane device, 
 in a third region of the backplane device that is different from the first region including the array of pixel circuits and the second region including the array of second pixel circuits, or 
 in a fourth region of the second backplane device that is different from a fifth region including the array of second pixel circuits. 
 
 
 
     
     
       6. The method of  claim 1 , wherein injecting laser pulses into particular first light emitting elements of the array of first light emitting elements comprises:
 sequentially injecting the laser pulses into the particular first light emitting elements by step by step moving the laser pulses to the particular first light emitting elements. 
 
     
     
       7. The method of  claim 1 , wherein a spot size of the laser pulses injected into the particular first light emitting element is
 no smaller than a size of the particular first light emitting element and 
 no larger than a sum of the size of the particular first light emitting element and twice of a gap between two adjacent first light emitting elements. 
 
     
     
       8. The method of  claim 1 , wherein two adjacent pixel circuits in the backplane device are separated by a dielectric spacer,
 wherein adjacent first light emitting elements in the array of first light emitting elements are separated by a gap having a size no larger than a size of the dielectric spacer, and 
 wherein each of the first light emitting elements has a size
 no smaller than a size of each of the pixel circuits and 
 no larger than a sum of the size of the pixel circuit and twice of the size of the dielectric spacer. 
 
 
     
     
       9. The method of  claim 1 , wherein integrating the first light emitting elements on the first substrate with the backplane device comprises:
 pretreating with plasma activation at least one of surfaces of the respective first intermediate metallic layers for the first light emitting elements or surfaces of the conductive outer layers of the array of pixel circuits. 
 
     
     
       10. The method of  claim 1 , wherein integrating the first light emitting elements on the first substrate with the backplane device comprises:
 detachably bonding surfaces of the respective first intermediate metallic layers for the first light emitting elements with surfaces of the conductive outer layers of the pixel circuits. 
 
     
     
       11. The method of  claim 1 , wherein forming an array of first light emitting elements and respective first intermediate metallic layers on a first substrate comprises:
 epitaxially growing multiple first semiconductor films on the first substrate to form a first light emitting structure; 
 forming a first intermediate metallic film on top of the first light emitting structure on the side further from the first substrate; and 
 patterning the first light emitting structure and the first intermediate metallic film to form the array of first light emitting elements with the respective first intermediate metallic layers. 
 
     
     
       12. The method of  claim 11 , wherein patterning the first light emitting structure and the first intermediate metallic film comprises:
 patterning the first light emitting structure and the first intermediate metallic film according to a pattern of the array of pixel circuits in the backplane device, such that each of the array of first light emitting elements is integrated on a respective one of the array of pixel circuits in the backplane device. 
 
     
     
       13. The method of  claim 1 , further comprising:
 before the integrating, aligning the array of first light emitting elements with the array of pixel circuits in the backplane device. 
 
     
     
       14. The method of  claim 1 , wherein integrating the array of first light emitting elements formed on the first substrate on an array of pixel circuits in a backplane device comprises:
 integrating the array of first light emitting elements with the array of pixel circuits in a first region of the backplane device, and 
 wherein the method further comprises:
 integrating another array of first light emitting elements on another first substrate with another array of pixel circuits in a second region of the backplane device, the second region being adjacent to the first region; 
 injecting the laser pulses into particular another first light emitting elements of another array of first light emitting elements, such that each of the particular another first light emitting elements is individually separated from the another first substrate and locally bonded with a respective particular another pixel circuit of the another array of pixel circuits through a respective particular another first intermediate metallic layer; and 
 removing the another first substrate from the backplane device, with the particular another first light emitting elements remaining bonded with and conductively coupled to the respective another particular pixel circuits in the second region of the backplane device. 
 
 
     
     
       15. The method of  claim 1 , wherein each of the pixel circuits comprises a non-volatile memory including at least one transistor conductively coupled to a corresponding drive electrode that is a conductive outer layer of the pixel circuit, the corresponding drive electrodes in adjacent pixel circuits being separated by dielectric spacers,
 wherein each of the first light emitting elements comprises a corresponding contact electrode as the first conductive outer layer, 
 wherein each of the particular first light emitting elements is conductively coupled to a non-volatile memory in the respective particular first pixel circuit through the corresponding contact electrode of the particular first light emitting element, the respective particular first intermediate metallic layer, and the corresponding drive electrode of the respective first particular pixel circuit, and 
 wherein the corresponding drive electrode has a size substantially same as a size of the particular first light emitting element. 
 
     
     
       16. The method of  claim 1 , wherein each of the first light emitting elements comprises:
 a buffer layer directly formed on the first substrate, 
 a first contact electrode formed on the buffer layer, 
 one or more quantum well layers as an active medium formed on the first contact electrode, and 
 a second contact electrode formed on the quantum well layers, the second contact electrode being the first conductive outer layer. 
 
     
     
       17. The method of  claim 1 , wherein the respective first intermediate metallic layer comprises one or more metallic films including:
 an iridium-tin-oxide (ITO) film with a titanium (Ti) film, 
 a cupper (Cu) film with a Tantalum (Ta) film, 
 an aluminum (Al) film with a Tin (Sn) film, or 
 a gold (Au) or silver (Ag) film with at least one adhesive film including chromium (Cr), Platinum (Pt), Palladium (Pd), or Titanium (Ti). 
 
     
     
       18. The method of  claim 1 , wherein two adjacent particular first light emitting elements bonded on the backplane device are separated by one or more second pixel circuits of the array of pixel circuits, and
 wherein the method further comprises:
 integrating an array of second light emitting elements with respective second intermediate metallic layers formed on a second substrate with the backplane device bonded with the particular first light emitting elements by contacting the respective second intermediate metallic layers to the second light emitting elements on conductive outer layers of the second pixel circuits, wherein each of the second light emitting elements on the second substrate is configured to emit light with a second color different from the first color and separated from each other by a space, and wherein the particular first light emitting elements bonded on the backplane device are enclosed within the spaces between the second light emitting elements; 
 injecting second laser pulses into particular second light emitting elements of the array of second light emitting elements, such that each of the particular second light emitting elements is individually separated from the second substrate and locally bonded with a respective particular second pixel circuit of the second pixel circuits through a respective particular second intermediate metallic layer; and 
 removing the second substrate from the backplane device, with the particular second light emitting elements remaining bonded with and conductively coupled to the respective particular second pixel circuits in the backplane device through the respective particular second intermediate metallic layers. 
 
 
     
     
       19. The method of  claim 18 , wherein a height of each of the array of second light emitting elements formed on the second substrate is substantially identical to a height of each of the array of first light emitting elements formed on the first substrate. 
     
     
       20. The method of  claim 18 , wherein each of the particular second light emitting elements is adjacent to a corresponding particular first light emitting element on the backplane device, and
 wherein a distance between the particular second light emitting element and the corresponding particular first light emitting element is no larger than a distance between adjacent pixel circuits in the backplane device. 
 
     
     
       21. The method of  claim 18 , wherein two adjacent particular second light emitting elements bonded on the backplane device are separated by one of the particular first light emitting elements boned on the backplane device and at least one third pixel circuit of the second pixel circuits of the array of pixel circuits, and
 wherein the method further comprises:
 integrating an array of third light emitting elements with respective third intermediate metallic layers formed on a third substrate with the backplane device bonded with the particular first light emitting elements and the particular second light emitting elements by contacting the respective third intermediate metallic layers on the third light emitting elements to conductive outer layers of the third pixel circuits, wherein each of the third light emitting elements on the third substrate is configured to emit light with a third color different from the first color and the second color and separated from each other by a second space, and wherein the particular first light emitting elements and the particular second light emitting elements bonded on the backplane device are enclosed within the second spaces between the third light emitting elements; 
 injecting third laser pulses into particular third light emitting elements of the array of third light emitting elements, such that each of the particular third light emitting elements is individually separated from the third substrate and locally bonded with a respective particular third pixel circuit of the third pixel circuits through a respective particular third intermediate metallic layer; and 
 removing the third substrate from the backplane device, with the array of third light emitting elements remaining bonded with and conductively coupled to the respective particular third pixel circuits in the backplane device through the respective particular third intermediate metallic layers. 
 
 
     
     
       22. The method of  claim 21 , wherein the particular first light emitting elements are conductively connected to the particular first pixel circuits to form first sub-pixels of active-matrix multi-color pixels,
 wherein the particular second light emitting elements are conductively connected to the particular second pixel circuits to form second sub-pixels of the active-matrix multi-color pixels, 
 wherein the particular third light emitting elements are conductively connected to the particular third pixel circuits to form third sub-pixels of the active-matrix multi-color pixels, 
 wherein each of the active-matrix multi-color pixels comprises a first sub-pixel having a particular first light emitting element and a particular first pixel circuit, a second sub-pixel having a particular second light emitting element and a particular second pixel circuit, and a third sub-pixel having a particular third light emitting element and a particular third pixel circuit, and 
 wherein the particular first, second, and third light emitting elements in each of the active-matrix multi-color pixels are adjacent and conductively isolated from each other, and the respective particular first, second, and third pixel circuits are adjacent and conductively isolated from each other. 
 
     
     
       23. The method of  claim 21 , further comprising:
 filling an isolation material in gaps between adjacent particular first, second and third light emitting elements that remain integrated on the backplane device, 
 wherein the isolation material comprises an opaque and conductively isolated dielectric material. 
 
     
     
       24. The method of  claim 23 , wherein each of the particular first, second, third light emitting elements comprises a first contact electrode as a conductive outer layer of the light emitting element and a second contact electrode formed on a buffer layer that is formed on a corresponding substrate, and
 wherein the method further comprises:
 planarizing the particular first, second, third light emitting elements with the isolation material filled in the gaps to remove the buffer layers to form a common surface with exposure of the second contact electrodes of the particular first, second, third light emitting elements. 
 
 
     
     
       25. The method of  claim 24 , further comprising:
 forming a transparent conductive layer on the common surface to form a common electrode for the particular first, second, and third light emitting elements.